Or a bacteria could be programmed to help lactose intolerant people digest lactose. Even plants could benefit. They could contain a bacteria that produces insecticide when they sense they're being nibbled on.

"You use a text-based language, just like you're programming a computer," Christopher Voigt, an MIT professor of biological engineering, said in a press statement. "Then you take that text and you compile it and it turns it into a DNA sequence that you put into the cell, and the circuit runs inside the cell."

Voigt and colleagues at Boston University and the National Institute of Standards and Technology have built biological circuits capable of measuring light, temperature, acidity, and other environmental conditions such as oxygen level or glucose.